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SHOTCRETE / SCL

What and How to supervise

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What is Shotcrete?

Concrete conveyed through a hose

and pneumaticallyprojected at highvelocityonto a surface, as a construction

technique.

Shotcrete undergoes placement and compaction at

the same time

There are now two different Sprayed Concrete

Processes:

Dry Process Sprayed Concrete

Wet Process Sprayed Concrete

http://en.wikipedia.org/wiki/Pneumaticshttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Pneumatics

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Dry Spray Application Wet Spray Application

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Spray Arm With Spraying Booth

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Wet Spray Application 1

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Wet Spray Application 2

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Dry Spray Application

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Thin-flow Process for

Dry-Sprayed Concrete

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Very Early Strength

from 0 to 1 N/mm with

needle penetration

Very Early Strength

from 1 to 15 N/mm

with bolt firing Mtehod

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Core Compression Testing

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Facto rs inf luencing the reboundquant i ty:

nozzlemanstechnical skill and experience

spraying direction (up, down, horizontally) spraying parameters (air pressure, nozzle,

spray output)

spraying process (dry/wet sprayed

concrete)

sprayed concrete mix design (aggregate,

grading curve, accelerator, fibers, binder)

sprayed concrete performance (very earlystrength, adhesive strength, layer thickness)

substrate condition (evenness, adhesion)

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Handling the Spray Nozzle for

an even Shotcrete Surface

The influence of the Spray

angle on the rebound

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The main mix requirement focus on the

workability (Pumping, SprayingApplication) and durability; they are:

High early strength The correct set Concrete characteristics

User-friendly workability (long open times)

Good pumpability (dense-flow delivery) Good sprayability (pliability)

Minimum rebound

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Driving Sprayed Concrete Laboratory

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Drift Wall advance

Preceding drift walls (1,2),followed by excavation ofthe crown (3) then bench

and invert (4) including safesupport in each case

Methods of Advance

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Excavation Profile Core Method Uetliberg

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Nozzle man Spraying manually Automatic Spraying head inoperation

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Sprayed Concrete Test for

Controlling Rebound

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MachinesPutzmeister Stationary Concrete

Pump Sika-PM702 E

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Putzmeister Stationary Concrete Pump

BSA 1002 D Multi

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Sika-PM500

D i U it

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Schematic cross-section

of Squeeze PumpAliva-403.5 Extended

Dosing Units

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Schematic Cross-section of

Aliva Rotor Machines

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Aliva 263 Extended

by Metering UnitAliva 246.5 Basic

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